Lubricant for metal rolling mills



Patented Mar. 24, 1953 UNIT ED STAT ES PATENT O FFICE LUBRICANT FOR METAL ROLLINGMILLS- Lorne W. Sprcule and Laurence F. King, Sarnia,

Gntario, Canada, assignors' to Standard Oil Development Company, a'corporation of Dela-- NoDrawing. Application March-30,1949,v Serial- No. 84,484

as in reversing type" rolling mills 'for example, may be considerably facilitated by the use of a lubricant containing specific ingredients. The.

power requirements for'rolling mill operation may be reduced asmuch as 25% or more, or'conversely, the amount of reduction in the thickness. of metal plate obtainable for each pass of the rollers may be increased without increasing thepower consumptionper pass. By this means; the number of passes required to reducea sheet of steel, for example, from a thickness of about 100/ 1000" to 10/ 1000" may be reduced very substantially.

In theprior art, emulsifiable or soluble oilshave long been used to lubricate the surface of the sheet metal, and thereby reduce rolling friction as well as to cool the sheet metal" and the rollers. An emulsion consisting of. water with about 1 to 30% by weight of em'ulsifiable oil therein is sprayed on the sheets as: they enter the rollers. The emulsifiable oil. ordinarily is cooled and recirculated for reuse; is required because of its high heat capacity whereas oilis essential for surface lubrication.

According to the present invention, by incorporating a widely varying quantity; as little as about 0.1% or as much as about 50% by weight, based on the total oil composition (excluding water), of an oilihess or extreme pressure agent into the oil and at the same time changing'its emulsification characteristics so that a relatively unstable emulsion is prepared, the reduction in power requirements or the capacity to obtain a greater reduction in thickness per pass may be accomplished. The quantity of emulsifier required will also vary widely, depending upon the other ingredients as well as upon the type of emulsifier.

While the reasons are not too clear why an unstable emulsion should be superiorto astable emulsion, the following explanation is offered as being plausible. .In a stable emulsion, the

mineral oil content in which an oiliness or ex treme pressure agent may be dissolved, is con tained in minute globules surrounded by the emulsifier. Emulsifiers commonly used. are cer-- tain soaps such as sodium naphthenate or sodi Th water um or' cal-ciumsulfonates which are oil-soluble or; at least oil dispersible,. and the like. Quantities of these may vary from about 2% to 30%. by weight of the total oil composition. Other surface active materials may be used With or in lieu of the soaps-or sulionates, e. g. partial C12 to C24 fatty acid esters of pclyhydric alcohols, and the like. Smaller quantities of these are suitable.

With a stable emulsion there areiew if any free. particles of oil'priesent which are nctprotected by the soap or other emulsifier. Apparently, when the metal'being rolled comes in contact with such an'emulsion, little, if any, oil is. held by or'ads'orbed to the metalbe'c'ause of. the presence on the metal surface of a protecting filrn of soap, sulfon'ate, or'other emulsifier. As a result, there is no surface chemical reaction which can take place directly between the outer layer of molecules'ofv metaland the oilinessor extreme pressure agent. Thus, if the oil. contains anextreme pressure agent, such as-a phosphorus compound, the emulsifier prevents-the immediate reactionbetween phosphorus and steel which would occur spontaneously at the high instantane'cus temperatures at point of rolling contact. reaction, when it occurs, forms a surface layer oi iron phosphide for example, which appears to have a much lower resistance to rollingthan the: iron car-bide, or.

the like, which iscommonly presenton the 'sur face of arolled steelplate.

0n theother hand,where-the-emulsion is unstable, the oil separates-almost instantaneously from the emulsion asthe spray strikes thesurface of the. metal. At the line of rolling contact, the extreme pressure between the plate being rolled and the roller surface causes an instantaneous rise.in@ temperature with the resuit that the extreme pressure additive immediate1yreaets witn the surface molecules of the I plate and the resulting reacted: film, for example, iron phosph-ide or sulfide, is much more readily deformed with the same expenditure of energy. Oiliness agents-likewise may'react with.

the metal to form soaps with the same general result. There is someevidence that the soap forming reaction at the rolling temperature is more effective than the conventional phosphicle orv sulfide reaction.

Thus, it appears that when an emulsifiable oil containing the oiliness orv extreme pressure agent is formulated. so as to give an. unstable ornmarginally stable. emulsion. in. water, the oil can be adsorbed by the plate and is effective immediately to reduce friction under boundary conditions of lubrication.

While the above explanation appears to apply specifically to rolling operations, which reduce the thickness of sheet and plate metals, it appears also to have possible application to other metal working operations such as machining, threading, tapping, etc. The essential requirements, for rolling mill lubrication at least, appear to be that the oil shall contain enough of an effective emulsifier to form a true emulsion but that the quantity shall be insufficient to make a stable emulsion. Since the emulsion is circulated in most commercial practice, there is little difficulty in keeping the oil and water sufiiciently agitated to retain the emulsion until it can be sprayed or otherwise applied on to the metal ahead of the line of rolling contact. The following specific examples show experi-, mental compositions which gave various results. They demonstrate the difficulty of predicting the results that might be obtained by varying the quantity and types of load carrying agents in the oil. They point clearly, however, to the beneficial efiects of controlled emulsification.

EXAMPLE A Formula Per cent by weight Sodium sulfonate concentrate (65% sulfonate, 35% mineral oil) 20.6 Naphthenic acids 3.25 Sodium hydroxide 0.5 Water 2.15 Alcohol 0.5 Candelilla wax 0.05 Mineral oil, F S. U. S. vis. at 210 F 72.95

This composition is an emulsifiable oil which forms a stable emulsion with water. It was used as a standard in comparing subsequent examples for their effectiveness as metal rolling lubricants.

EXAMPLE B Per cent by weight Sodium sulfonate concentrate (65% sulfonate 35% mineral oil) 24.0 Naphthenic acids 3.25 Sodium hydroxide 0.5 Water 2.15 Alcohol 0.5 Candelilla wax 0.05

1 Mineral oil, 89 S. U. S. vis. at 210 F 69.55

This composition is similarly emulsifiable. It showed no improvement over Example A in the rolling of sheet steel.

EXAMPLE C Per cent by weight 'Sodium sulfonate concentrate (65% sul- This example was prepared todetermine whether the addition of an extreme pressure agent (sulfurized mineral and elaine oil) would 7 slight improvement was 76.

ofier substantial improvement. Results were negative.

EXAMPLE D Per cent by weight Sodium sulfonate concentrate (65% sul- Like Example C, this example failed to show improvement over the base oil (Example A), notwithstanding the inclusion of a large amount of extreme pressure additive (10% sulfurized sperm oil). The addition of a load bearing agent per se does not solve the problem.

EXAMPLE E Per cent by-weight sodium sulfonate concentrate (65% sulfonate, 35% mineral oil) 13.7 Naphthenic acids 2.2 Sodium hydroxide 0.37 Water 1 0.5 Diethylene glycol 1.1 Mineral oil 50 S. U. S. vis. at 210 F 56.75 Sperm oil 25.0

This example was similar to'Example A except for sperm oil. The use of a very large quantity of an oiliness agent is not effective. Sperm oil is a very good oiliness agent and was used to replace 25% of the mineral oil, withoutbeneficial results.

EXAMPLE F Per cent by weight Sodium sulfonate concentrate (65% sulfonate, 35% mineral oil) 13.7 Naphthenic acids 2.2 Sodium hydroxide 0.37 Water 0.5 Diethylene glycol 1.1 Mineral oil 50 S. U. S. vis. at 210 F .2. 71.75 Tricresyl phosphate 5.0 Sorbitan trioleate 5.0

Tricresyl phosphate is an excellent oiliness agent for many applications but was ineffective here. The sorbitan trioleate was used in addition to the sodium sulfonate as an emulsifier. For some applications this example is a superior lubricant, but it showed no advantages over Example A as a steel rolling lubricant.

EXAMPLE G Per cent by weight Oleic acid 30.0 Alkylene oxide derivative of sorbitan monooleate 15.0 Triethanolamine 7.5 Mineral oil 50 S. U. S. vis. at 210 F 47.5

In this example, the oleic acid was only partly saponified, about half being present as free oleic acid, an excellent oiliness agent. The composition was readily emulsifiable however, because of the large soap content, and showed no substantial improvement over Example A. A very noted. Compare the next example.

amasse- Bercentbywei-gh t oleic acid 10.0."

In hiwee m h 01 1p. ac diw nl par l saponified' by the triethanolamine, leaving about half; as, free oleic acidto serve as anoiliness agent; The quantity ofsoap was ,insufiicient for complete emulsification and this appears to be the reason that this composition showed very superior results in the rolling of steel sheet. This composition showed 5 cc. separation from 100 cc. of emulsion in water after one-half hour.

EXAMPLE J Per cent by weight Sodium sulionate concentrate (55% sulfonate, 35% mineral oil) 14.0 Naphthenic acids 2.25 Sodium hydroxide 0.35 Water 0.10 Diethylene glycol 1.1 Sperm oil 32.0 Mineral oil, 180 S. U. S. vis. at 210 F 50.2

Example J was characterized by a heavy mineral oil base. The quantities of sperm oil, as oiliness agent, and of sodium sulionate, as emulsifier, were rather high, but the composition formed an unstable emulsion in water, showing 7 cc. separation from 100 cc. of 10% emulsion in water. This product gave 0.001 additional reducticn in thickness of rolled steel sheets per pass, as compared with Example A. The composition of Example H performed similarly, demonstrating outstanding improvement in these unstable emulsion products.

The data are summarized in the following table:

6 an sare veryssienifiuant ndsmawbeasmuch;as 25; 0131110119.;

In. general; thegquantityof: emulsifying; agent; to; make they unstable-,or marginal; emulsinn do:

. sired:wilrbesbetweenpl and-.3056. ofithe Weight of; theemulsifi-able oil, depending "upon the 0th n redients. The-C12: 1103024. p rtial-u polyhydric alcohols, such as sorbitan r: mono er; dis ea-rate bez d 'a agents in proportionspofs. about; by weightor the alkali or alkaline ea sulionates. which are oil soluble, somewhat larger proportions. combination oroil solnble metal sulfonates and' polyhydric alcoholiestersof the type mentioned appears to be preferable.

Other suitable emulsifying agents are soaps such as sodium or an amina lea e sashe rieth: anol a rn ine o 1 eat e. Where the partial esters and the sulffonates or soaps are both used, the proportions may vary from 'about 0 to 30% of soap and 0 to 10% of the esters. The quantities preferred are intermediate of these limits.

Specifically, with oils of the types given in Examples H and J, the emulsifiers are about 15 to 18% soap and about 1 to 1.5% glycol (Example J) or about 7 to 8% of the soap triethanolamine oleate.

The oiliness or extreme pressure agents may be referred to generically as load carrying agents. Either may be used, or a combination thereof. The esters of the acids of phosphorus (phosphates and phosphites) as well as the glyceride esters of fatty acids (the common fatty oils), fatty acids and sulphurized fatty acids, and the like are useful as oiliness agents and Various extreme pressure additives such as sulfurized and/or phosphorized fatty oils, fatty acids, aliphatic esters, and the like, and the halogenated hydrocarbons, or combinations thereof may be used, as is Well understood by those skilled in the art. Tricresyl phosphate, tributyl phosphate, sperm Table 1 Example A B C D E F G H I 107 Emulsion cc. separation no separa- 1cc no separan0 separatrace. no se amno se ai ter hour tion. mm. mm l 5 7 cc. Roll Tests (further reduction in thickness in comparison to Exittt- B1 1:

iulon an n (L0 H u 10:1 Dilution do 1111-. m1 n11 In summary, it Will be noted that in Examples A to G inclusive, which form stable emulsions with water there was little variation and no particular advantage in the substitution of various load carrying agents. Thus, the use of waxes, fatty oils, sulfurized fatty oil, tricresyl phosphate, fatty acids and the like, did not appear to make any particular difference in the reduction in thickness for each pass of a steel sheet between rollers. Various dilutions of oil were used, as much as 10%, and high quantities of fatty oil, for example 25% of sperm 011, showed no significant difierences.

However, when the quantity of emulsifier was reduced so that 5 to 7 cc. of oil separated from 100 cc. of a 10% emulsion of the oil in water in one-half-hour, as in Examples H and J a considerable improvement in rolling effectiveness was obtained. The reductions of about /1000" per pass above conventional lubricants which were obtained are considered highly satisfactory. The power savings to be obtained from such lubrioil, and closely related materials are specifically preferred as oiliness agents.

What is claimed is:

1. An emulsifiable oil composition of the following approximate formula:

Per cent by weight Sodium sulfonate concentrate (65% sulfonate 35% mineral oil) 14.0

2. The process of lubricating metal rolling operations which comprises applying immediately ahead of the line of rolling contact an aqueous emulsion of a composition containing lubricating oil, a load bearing agent and an emulsifying agent added in an amount sufficient to form a marginally stable, complete emulsion of said composition in water, said emulsion having an equivalent stability such that at least about 50% of said composition separates after 0.5 hour from a. 10% emulsion of the composition in the water said emulsion having the property of breaking substantially as it strikes the metal being rolled.

3. An emulsifiable composition having the approximate formula by weight:

15 to 18% soap comprising a major proportion of oil soluble petroleum sulfonate and a minor proportion of sodium naphthenate,

1 to 1.5% diethylene glycol,

About 0.1% Water,

About 32% sperm 011,

Balance, mineral lubricating oil.

LORNE W. ,SPROULE.

LAURENCE F. KING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,245,649 Caprio June 17, 1941 2,342,199 Hurtt Feb. 22, 1944 2,353,830 Kaufman et a1 July 18, 1944 2,432,784 Miller Dec. 16, 1947 2,470,405 Leland May 17, 1949 2,470,913 Bjorksten May 24, 1949 

1. AN EMULSIFIABLE OIL COMPOSITION OF THE FOLLOWING APPROXIMATE FORMULA:
 2. THE PROCESS OF LUBRICATING METAL ROLLIN OPERATIONS WHICH COMPRISES APPLYING IMMEDI ATELY AHEAD OF THE LINE OF ROLLING CONTACT AN AQUEOUS EMULSION OF A COMPOSITION CONTAINING LUBRICATING OIL, A LOAD BEARING AGENT AND AN EMULSIFYING AGENT ADDED IN AN AMOUNT SUFFICIENT TO FORM A MARGINALLY STABLE, COMPLETE EMULSION OF SAID COMPOSITION IN WATER, SAID EMULSION HAVING AN EQUIVALENT STABILITY SUCH THAT AT LEAST ABOUT 50% OF SAID COMPOSITION SEPARATES AFTER 0.5 HOUR FROM A 10% EMULSION OF THE COMPOSITION IN THE WATER SAID EMULSION HAVING THE PROPERTY OF BREAKING SUBSTANTIALLY AS IT STRIKES THE METAL BEING ROLLED. 